HTSew · Use of HTC technology as an innovative reuse method for sewage sludge

Efficient municipal wastewater treatment, such as the systems currently in place in most European municipalities, produces vast amounts of sewage sludge. The latest data collected show a yearly production of 9.637 thousands of tons in the EU28 countries. Sludge treatment issues are often neglected in comparison with water-related parameters which results in serious technical difficulties and highly expensive disposal methods. As a result, an energy efficient, environmentally sound and economically viable process for sludge disposal hardly exists.The most common disposal methods for sludge are spreading on agricultural soil, composting and incineration. Landfilling has been long banned, the use as fertilizer, although very moderate in costs, is being banned in many regions due to concerns about contamination of soils with heavy metals and endocrine disruptive compounds. Composting raises the same concerns, and it is a labor-intensive and unsafe process, which leaves incineration as the most used option, albeit an expensive and not effective one. Incineration entails the highest costs (80-110 € /ton), but is also considered the safest disposal method and is fast growing and widely adopted. It presents also technical difficulties, such as the low overall efficiency of the process, the huge logistic efforts required to transport the sludge to the incineration plants, or the disposal of the ashes after the sludge has been incinerated.In this situation, the proposing company, Ingelia, has the objective to demonstrate and commercialize their proprietary technology for hydrothermal carbonization (HTC) to the conditions of sewage sludge, showing clearly technical and economic advantages compared to incineration. Ingelia aims to increase the amount of sludge converted into high value products such as fuel or activated carbons for water treatment. The HTSew process turns the sewage sludge disposal from a costly process into an income-generating activity.